Abstract
In recent years, control of group velocity of light has attracted enormous interest. One of the main challenges is to realize an absorption-free fast or slow light propagation. Here, we study dispersion and absorption properties of a weak probe field in a Landau-quantized graphene and report a gain-assisted superluminal light propagation. Moreover, an attempt is made to develop an analytical expression and necessary parameters for switching the group velocity of the probe field from subluminal to superluminal. It’s worth mentioning that large dephasing rate in graphene offers feasibility of superluminal propagation of ultrashort light pulses. Additionally, dynamical behavior of dispersion and absorption of a weak probe field in a closed-type graphene system is investigated, and it is found that the absorption and dispersion can be dramatically affected by both the relative phase of applied fields and the Rabi frequencies in such a way that a large transient gain can be achieved and a transient absorption can be completely eliminated.
Highlights
Graphene, as the thinnest material known in the universe,[1] consists of carbon atoms in a twodimensional (2D) hexagonal lattice with unusual Dirac-like electronic excitations
We proceed to rewrite density matrix equations for the case of a closed-loop configuration, in which the system becomes quite sensitive to the relative phase of applied fields
Our model shows a wide range of tunability so that a large transient gain and steady-state absorption can be achieved, compared to their suggested scheme
Summary
As the thinnest material known in the universe,[1] consists of carbon atoms in a twodimensional (2D) hexagonal lattice with unusual Dirac-like electronic excitations. It holds many records related to mechanical, thermal, electrical and optical properties.[2,3] Besides, its band-gap structure can be tuned by voltage or chemical doping, through which conductivity and transmission are changed. This feature can endow graphene with a capability of operation in both terahertz and optical frequency ranges. These achievements demonstrate the feasibility of graphene for applications such as chip-scale high-speed optical communications, all-optical signal processing, photonics and optoelectronics
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